This invention relates generally to the of hydrocarbons from wells and also to the sensing of the various pressures and control of flow of fluids that are present in wells that have been completed for hydrocarbon production. By hydrocarbon it is intended to mean oil, gas, and gas condensate. More particularly, the present invention concerns wells that have been drilled to various, perhaps multiple, isolated subsurface zones, including wells having lateral deviated branches to specific subsurface zones and for selectively controlling the production of hydrocarbon products from those zones by controlling the selective opening and closing of isolation valves that may be located in the main wellbore, branch wellbores or both.
In the past, most wellbores for production of petroleum products were drilled substantially vertically from the surface for intersection of a subsurface potential hydrocarbon producing zone of interest. More recently, well drilling practices have been modified to drill deviated wellbores from a particular surface location, such as in an offshore drilling and production platform, for example. In this case, each well drilled from the platform is typically drilled vertically to a desired depth and then is deviated at an angle to a potential hydrocarbon production zone of interest. Deviated wellbores may also be drilled horizontally or near horizontally from a vertical or near vertical wellbore, so as to intersect a zone of interest and to ensure the location of a substantial length of the wellbore within the selected subsurface formation, such as a hydrocarbonaceous formation, for example. Typically, for the drilling of deviated and substantially horizontal wellbores wide use is made of drilling using mud motors which are energized by flowing drilling fluid. The mud motors, especially in the case of horizontal wellbores are typically connected to a flexible coiled tubing which is not rotated within the wellbore during drilling. The flexible coiled tubing through which drilling mud is pumped, simply is moved linearly through the wellbore and the rotating mud motor and its drill bit progress through the subsurface formation being drilled.
Even more recently, wells have been drilled and completed to multiple zones of interest by drilling a primary wellbore, which may be typically but not necessarily vertically oriented and by then drilling one or more lateral branch wellbores that deviate from the primary wellbore and intersect particular zones of interest. In this manner, a single well can be drilled and two or more isolated potential hydrocarbon producing zones of interest may be produced from the single well. The production fluid of one zone can be kept separate from the production fluid of another zone if such is desired by zonal isolation. Zonal isolation refers to the separation from the production tubing of the isolated production fluid from zones in a cased or open wellbore. This is usually accomplished by the use or packers of plugs set within the casing, or in an open hole section, to prevent fluid communication via the casing or the borehole from one such zone to another.
Where multiple zones of interest are intersected by offset or branch bores from a primary wellbore, it is often desirable to complete the well in each of the subsurface hydrocarbon production zones of interest, but to insure that each zone of interest is maintained completely isolated from other zones of interest. The separated zones are each completed into the branch bores or into separate production tubing extending from the primary wellbore or the surface. The present invention is directed to a retrievable zonal isolation control system for use in wells of this nature, wherein each of several production zones may be selectively and independently produced by selectively controlling the open and closed positions of isolation valves that are provided for each of the subsurface zones.
It is a feature of the present invention to provide a novel zonal isolation control system for wells having offset or branch bores penetrating isolated subsurface hydrocarbon production zones and which provides for zonal isolation control so that the well can be produced selectively from one or more, of the subsurface zones in an independent manner.
It is another feature of the present invention to provide a novel retrievable zonal isolation control system having isolation control apparatus that is located within respective isolation mandrels permanently attached in the well production tubing and which have sensor or control modules which may be installed and retrieved by wire-line equipment.
An additional advantage of the system of the invention is that larger total well control packages than usual may be employed without fear of failure, since individual components can be replaced in situ.
It is a further feature of the present invention to provide a novel retrievable zonal isolation control system for multiple offset or branch wells wherein control valves therefor may be in the form of rotary valves, sliding sleeve valves, gate valves or another suitable valve type and wherein the valves may be hydraulically or electrically actuated and electrically controlled via electric wire lines extending to surface control equipment or are controlled in situ in a well by power sources, such as replaceable batteries, that are located onboard the respective zonal isolation control apparatus.
Another feature of the present invention is to provide a novel retrievable zonal isolation control system having electronic circuitry and being capable of being installed within and being retrievable inside production tubing from a permanently emplaced bottom entry mandrel which has a wet-connect, and/or inductive or capacitive type electrical connection for electrically connecting the circuitry to electrical conductors that extend to the surface or from component module to component module of the system.
Briefly, the system of the present invention provides the above referenced and other features in a through tubing sized set of electronic sensor, power, and control modules which may be set in the wellbore or retrieved therefrom by the use of a kick over tool into a permanently installed side pocket mandrel equipped section of tubing. The well to be controlled is drilled and cased to the desired depth of one or more producing zones. It will be understood by those of skill in the art that each potential hydrocarbon producing zone in the well is penetrated by the main, or an offset or branch bore, as previously described. Each zone is penetrated by one or more strings of production tubing. The hydrocarbon producing zones are isolated from fluid communication with each other inside the well casing or the borehole by sets of packers or plugs run into the well on the production tubing. Also permanently installed and carried by the production tubing are one or more side pocket mandrels which may be selectively placed in fluid and pressure communication with the casing/tubing or borehole/tubing annulus in the production zone in which they are located. These side pocket mandrels are equipped with wet connectors which can be used to establish electrical connection to power instruments and control modules which may be placed into their side pockets, or retrieved from them, by use of a kick over tool which may be run into the well tubing on a wire line. The permanently emplaced side pocket mandrels are also electrically interconnected to each other and to the surface if desired via electric wire lines which are run into the well attached to the production tubing. They may also have a hydraulic line connection to each other and possibly to the surface, which may also be run into the well on the production tubing. Isolation control modules or subs may also be run into the well via the kick over tool and installed or retrieved from the side pocket mandrels. Ball valve subs, sliding sleeve valve subs, flapper valve subs, rotary valve subs, linear valve subs, rotary plunger valve subs and in general, any type of fluid flow control valve sub may be placed in the well in a side pocket mandrel in this manner.
Also, modules for controlling production tubing carried hydraulic systems powered by downhole electrical motor powered hydraulic pumps are contemplated in the system of the invention. While such pumps may be too large to pass through tubing themselves and may be permanently carried by the tubing, their control may be provided by through tubing sized electronic modules placed in nearby side pocket mandrels. Such hydraulic fluid pumps (electrically powered) may be used, for example, to inflate or deflate resettable cased hole or open hole packers used in zonal isolation. Such hydraulic pump control modules (or other control modules) may be thought of as the xe2x80x9cbrainxe2x80x9d of the control system while the pumps, packers, valves, etc. controlled by them may be thought of as the xe2x80x9cmusclexe2x80x9d of the system.
In operation, when the well is completed and the production tubing run in, the packers or plugs are set isolating the various producing zones. The downhole instrument and control modules measure the casing/annulus or borehole/annulus and tubing pressures and supply the data via wireline to a control computer, located either at the surface of the earth or in one or more of the downhole modules. The control computer determines the fluid flow conditions in each isolated zone and sends control signals out to the valve module for that zone. Each valve module opens, adjusts, or stops fluid flow from the casing/tubing or borehole/tubing annulus into the production tubing in response to this control signal.
The operation of the system is best understood by reference to the following detailed description when taken is conjunction with the accompanying drawings which are illustrative and not limitative of the invention.